Research Overview

Research in the Auditory Processing Laboratory investigates the encoding, representation, and transformation of acoustic information within the auditory system. The goal is to understand how the brain represents and perceives the acoustic environment and how the neural systems in the brain are organized to create this representation. Our approach combines single- and multi-unit recording and analysis techniques, pharmacological manipulations, and computer modeling studies.

Current interest centers on the inferior colliculus (IC) because it occupies a pivotal position in the central auditory system; it receives direct inputs from most, if not all, of the auditory nuclei in the brainstem and, in turn, provides nearly all of the input to the auditory forebrain. Anatomical evidence suggests that the projections to the IC form highly organized synaptic domains with both segregated and shared sources of input. In support of this parallel processing model, our recent electrophysiological studies have discovered three principal IC response types that appear to be uniquely specialized for the neural encoding of spectral cues for sound localization, narrowband signals in noise, and binaural level and timing information. Based on correlations with response properties in lower-order nuclei, it has been hypothesized that each IC unit type reflects a dominant excitatory input from the medial superior olive, the lateral superior olive, or the dorsal cochlear nucleus. We are now performing experiments designed to provide direct evidence for these functional connections. In addition, we are exploring the functional consequences of this synaptic organization by comparing the quality of acoustic representations in IC target neurons and their sources of input. A question of particular interest in these latter experiments is how the ascending inputs to the IC interact with each other and a rich intrinsic inhibitory circuitry to enhance the processing of sound localization information.

Undergraduate

• NSCI 201P:  Basic Lab in Neurobiology
• NSCI 301:  Senior Seminar
• BCSC 204:  Lab in Cognitive Neuroscience
• NSCI/BCSC 243:  Neurochemical Foundations of Behavior
• NSCI/BCSC 244:  Neuroethology
• NSCI/BCSC 246:  Biology of Mental Disorders

Selected Publications

Journal Articles

• Greene NT, Davis KA. "Discharge patterns in the lateral superior olive of decerebrate cats." Journal of neurophysiology.. 2012 Oct 0; 108(7):1942-53. Epub 2012 Jun 27.
• Kanold PO, Davis KA, Young ED. "Somatosensory context alters auditory responses in the cochlear nucleus." Journal of neurophysiology.. 2011 Mar 0; 105(3):1063-70. Epub 2010 Dec 22.
• Greene NT, Lomakin O, Davis KA. "Monaural spectral processing differs between the lateral superior olive and the inferior colliculus: physiological evidence for an acoustic chiasm." Hearing research.. 2010 Oct 1; 269(1-2):134-45. Epub 2010 Jun 30.
• Lomakin O, Davis KA. "On the role of the wideband inhibitor in the dorsal cochlear nucleus: a computational modeling study." Journal of the Association for Research in Otolaryngology : JARO.. 2008 Dec 0; 9(4):506-20. Epub 2008 Aug 14.
• Davis KA, Lomakin O, Pesavento MJ. "Response properties of single units in the dorsal nucleus of the lateral lemniscus of decerebrate cats." Journal of neurophysiology.. 2007 Sep 0; 98(3):1475-88. Epub 2007 Jul 25.
• Davis KA. "Contralateral effects and binaural interactions in dorsal cochlear nucleus." Journal of the Association for Research in Otolaryngology : JARO.. 2005 Sep 0; 6(3):280-96.
• Davis KA. "Spectral processing in the inferior colliculus." International review of neurobiology.. 2005 70:169-205.
• Davis KA, Ramachandran R, May BJ. "Auditory processing of spectral cues for sound localization in the inferior colliculus." Journal of the Association for Research in Otolaryngology : JARO.. 2003 Jun 0; 4(2):148-63.
• Davis KA. "Evidence of a functionally segregated pathway from dorsal cochlear nucleus to inferior colliculus."Journal of neurophysiology.. 2002 Apr 0; 87(4):1824-35.
• Ramachandran R, Davis KA, May BJ. "Rate representation of tones in noise in the inferior colliculus of decerebrate cats." Journal of the Association for Research in Otolaryngology : JARO.. 2000 Sep 0; 1(2):144-60.
• Davis KA, Young ED. "Pharmacological evidence of inhibitory and disinhibitory neuronal circuits in dorsal cochlear nucleus." Journal of neurophysiology.. 2000 Feb 0; 83(2):926-40.

Book Chapters

• Chapter Title: Computational models of inferior colliculus neurons.
  Book Title: Computational Models of the Auditory System
  Author List: DAVIS KA, HANCOCK KE; DELGUTTE B.
  Edited By: R Meddis; EA Lopez-Poveda; AN Popper; RR Fay
  Published By: Springer-Verlag2010
• Chapter Title: Computational Models of Inferior Colliculus Neurons.
  Book Title: Computational Models of the Auditory System
  Author List: Davis, K.A, Hancock, K.E. and Delgutte, B.
  Edited By: R. Meddis, E.A. Lopez-Poveda, A.N. Popper, and R.R. Fay
  Published By: Springer-Verlag2009
• Chapter Title: Spectral processing in the inferior colliculus.
  Book Title: Auditory Spectral Processing<
  Author List: Davis, K.A.
  Edited By: M. Malmierca and D. Irvine.
  Published By: Elsevier Inc2005 in San Diego
• Chapter Title: Circuitry and function of the cat dorsal cochlear nucleus.
  Book Title: Integrative Functions in the Mammalian Auditory Pathway
  Author List: Young, E.D.; Davis, K.A.
  Edited By: D. Oertel, R. Fay, and A. Popper.
  Published By: Springer-Verlag2002
• Chapter Title: Representation of spectral cues for sound localization in the inferior colliculus.
  Book Title: Physiological and Psychophysical Bases of Auditory Function,
  Author List: Davis, K.A.; Ramachandran, R.; May, B.J.
  Edited By: D.J.Breebaart; A.J.M. Houtsma; A. Kohlrausch; et.al.
  Published By: Shaker Publishing2001 in Netherlands